Fine-Tuning of Catalytic Properties of Catechol 1,2-Dioxygenase by Active Site Tailoring

ChemBioChem ◽  
2009 ◽  
Vol 10 (6) ◽  
pp. 1015-1024 ◽  
Author(s):  
Raffaella Caglio ◽  
Francesca Valetti ◽  
Patrizia Caposio ◽  
Giorgio Gribaudo ◽  
Enrica Pessione ◽  
...  
Keyword(s):  
Active Site ◽  
Catalytic Properties ◽  
Fine Tuning ◽  
Catechol 1,2 Dioxygenase

scholarly journals A comparative study of class-D β-lactamases

1993 ◽  
Vol 292 (2) ◽  
pp. 555-562 ◽  
Author(s):  
P Ledent ◽  
X Raquet ◽  
B Joris ◽  
J Van Beeumen ◽  
J M Frère
Keyword(s):  
Active Site ◽  
Gene Sequence ◽  
Catalytic Properties ◽  
Ion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Beta Lactamase ◽  
Serine Residue ◽  
Beta Lactamases ◽  
Class D ◽  
Burst Kinetics

Three class-D beta-lactamases (OXA2, OXA1 and PSE2) were produced and purified to protein homogeneity. 6 beta-Iodopenicillanate inactivated the OXA2 enzyme without detectable turnover. Labelling of the same beta-lactamase with 6 beta-iodo[3H]penicillanate allowed the identification of Ser-70 as the active-site serine residue. In agreement with previous reports, the apparent M(r) of the OXA2 enzyme as determined by molecular-sieve filtration, was significantly higher than that deduced from the gene sequence, but this was not due to an equilibrium between a monomer and a dimer. The heterogeneity of the OXA2 beta-lactamase on ion-exchange chromatography contrasted with the similarity of the catalytic properties of the various forms. A first overview of the enzymic properties of the three ‘oxacillinases’ is presented. With the OXA2 enzyme, ‘burst’ kinetics, implying branched pathways, seemed to prevail with many substrates.

Catalytic properties of catechol 1,2-dioxygenase from Acinetobacter radioresistens S13 immobilized on nanosponges

2009 ◽  
pp. 6507 ◽  
Author(s):  
Giovanna Di Nardo ◽  
Carlo Roggero ◽  
Simona Campolongo ◽  
Francesca Valetti ◽  
Francesco Trotta ◽  
...  
Keyword(s):  
Catalytic Properties ◽  
Acinetobacter Radioresistens ◽  
Catechol 1,2 Dioxygenase

Fine Tuning of the Copper Active Site in Polysaccharide Monooxygenases

2020 ◽  
Vol 124 (10) ◽  
pp. 1859-1865
Author(s):  
Son Tung Ngo ◽  
Han N. Phan ◽  
Chinh N. Le ◽  
Nhung C. T. Ngo ◽  
Khanh Bao Vu ◽  
...  
Keyword(s):  
Active Site ◽  
Fine Tuning ◽  
Polysaccharide Monooxygenases

Investigation of the Catalytic Properties of the Dysthrombin, Thrombin Quick

1979 ◽  
Author(s):  
R.A. Henriksen ◽  
W.G. Owen ◽  
M.E. Nesheim ◽  
K.G. Mann
Keyword(s):  
Active Site ◽  
Mayo Clinic ◽  
Active Sites ◽  
Fluorescence Enhancement ◽  
Catalytic Mechanism ◽  
Antithrombin Iii ◽  
Catalytic Properties ◽  
Inhibitor Binding ◽  
Equivalent Number ◽  
Aggregation Of Platelets

Thrombin Quick (TQ) may be isolated following treatment of Prothrombin Quick [Owen, et al, Mayo Clinic Proceedings, 53: 29-33, (1978)] with Taipan venom, phospholipid and Ca2+. The clotting activity of TQ with fibrinogen is 1/200 that of normal thrombin (T) The activation of Factors V and VIII, and the aggregation of platelets by TQ occurs with an effectiveness of about 1/50 that of thrombin. When incubated with antithrombin III, both T and TQ form inhibitor complexes as determined by dodecylsulfate gel electropheresis. Titration of T and TQ with the fluorescent inhibitor dansylarginine-4-ethylpiperidine amide indicates an equivalent number of active sites based on protein absorption at 280 nm. However, the two enzymes may be distinguished by the decreased fluorescence enhancement observed with TQ relative to T, indicating an increased polarity in the inhibitor binding site of TQ. With the substrate benzoylarginine ethylester, TQ has a Km = 4.5 x 10-5M and kcat - 6.93 compared to Km = 4.0 × 10-5M and kcat = 17.7 for T. This indicates that the defect in TQ esterase activity is in the catalytic mechanism itself and not in substrate binding. The rate of inhibition of TQ by diisopropylphosphofluoridate is decreased. Decreased acylation and deacylation rates for TQ relative to T are observed for tydrolysis of the active site titrant 4-methyumbel1 i feryl-p-guanidlnobenzoate.

Catalytic properties of key active site mutants of flavocytochrome P-450 BM3

1999 ◽  
Vol 27 (1) ◽  
pp. A44-A44 ◽  
Author(s):  
M.A. Noble ◽  
C.S. Miles ◽  
G.A. Reid ◽  
S.K. Chapman ◽  
A.W. Munro
Keyword(s):  
Active Site ◽  
Catalytic Properties ◽  
Active Site Mutants

scholarly journals (−)-Homosalinosporamide A and Its Mode of Proteasome Inhibition: An X-ray Crystallographic Study

Marine Drugs ◽  
2018 ◽  
Vol 16 (7) ◽  
pp. 240 ◽  
Author(s):  
Michael Groll ◽  
Henry Nguyen ◽  
Sreekumar Vellalath ◽  
Daniel Romo
Keyword(s):  
Natural Product ◽  
Active Site ◽  
Late Stage ◽  
Enzyme Assay ◽  
Proteasome Inhibition ◽  
Fine Tuning ◽  
Synthetic Approach ◽  
X Ray ◽  
Salinosporamide A ◽  
Crystallographic Study

Upon acylation of the proteasome by the β-lactone inhibitor salinosporamide A (SalA), tetrahydrofuran formation occurs by intramolecular alkylation of the incipient alkoxide onto the choroethyl sidechain and irreversibly blocks the active site. Our previously described synthetic approach to SalA, utilizing a bioinspired, late-stage, aldol-β-lactonization strategy to construct the bicyclic β-lactone core, enabled synthesis of (–)-homosalinosporamide A (homoSalA). This homolog was targeted to determine whether an intramolecular tetrahydropyran is formed in a similar manner to SalA. Herein, we report the X-ray structure of the yeast 20S proteasome:homoSalA-complex which reveals that tetrahydropyran ring formation does not occur despite comparable potency at the chymotrypsin-like active site in a luminogenic enzyme assay. Thus, the natural product derivative homoSalA blocks the proteasome by a covalent reversible mode of action, opening the door for further fine-tuning of proteasome inhibition.

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